A mediastinal ependymoma in a 35-year-old Caucasian woman is reported. The tumor was located in a paravertebral posterior mediastinal location. No continuity with the spinal canal or with the lung was identified. The diagnosis was confirmed by immunoperoxidase staining for glial fibrillary protein and by the presence of cilia within intracytoplasmic vacuoles. To the best of our knowledge, this is the second reported case of ependymoma in this location.